ACTA1 and myocardial infarction: To evaluate correlation between increased scar area and miR‐145‐mediated myofibroblast differentiation, hearts of WT and KO mice at Day 7 after MI were used for immunofluorescent staining for α‐SMA, to determine the extent of transdifferentiation of cardiac fibroblasts into myofibroblasts (Figure 3E).